Learn Italian: Ho voglia di uno spuntino. - I feel like having a snack.

In Italian, physical states and urges often use the verb avere (to have). The phrase avere voglia di literally means 'to have the desire of', but it is the standard way to say 'to feel like' or 'to crave'. Because the sentence is about yourself ('I'), you use ho (I have).

Why do we need the word di here?

The idiom is always avere voglia di. Whenever you say you feel like something, you must connect voglia to the thing you want using di (of).

Why is the article uno instead of un?

Because of the word spuntino. It is a masculine noun that starts with an 's' followed by another consonant ('p'). Italian requires the article uno for masculine words starting with 's + consonant' (as well as 'z', 'gn', and a few others) to make pronunciation smoother.

How do I pronounce ho?

The 'h' is completely silent, so it sounds exactly like the Italian vowel 'o'. The 'h' is only written to visually distinguish ho (I have) from o (or).